1. Field of the Invention
The present invention relates in general to an RFID reader and in particular to a RFID reader with a capability to read different formats of RFID tags, including Intellitag “Gamma” and ISO/AAR RFID protocols.
2. Description of Related Art
An RFID reader broadcasts RF energy over an adjustable area called a read zone or reader footprint. An RFID tag, for example on a vehicle or package, reflects a small part of the RF energy back to the antenna of the reader. The reflected radio waves modify depending upon data stored on the RFID tag. The reader detects the modified radio waves and is able to decode the unique identification code or stored data located on the RFID. The technology for reading and alternatively writing data from and into a remote RFID is described in detail in U.S. Pat. Nos. 4,739,328; 4,782,345; 4,786,906; 4,816,839; 4,835,377; 4,853,705; 4,739,328 and 5,030,807 all hereby incorporated by reference. Previous readers have been able to read variations of the ISO/AAR protocol (International Organization for Standardization 10374.2 standard for intermodal freight containers/Association for American Railroads S-918 mandated standard for automatic equipment identification). A newer form of RFID tag utilizes “Gamma” technology. Representative of this form of RFID format is the Intellitag 500. In contrast with previous ISO/AAR formats the Intellitag 500 for Gamma technology RFID utilizes a differently modulated RF signal created by driving series RF mixers in the RF source section of the RFID reader transmitter. The Intellitag 500 format RFID being easier and cheaper to manufacture, it is expected to have an increasing market share. However, a large number of existing ISO/AAR format RFIDs are already in use.
Therefore, it is object of the present invention to create an RFID reader capable of reading both ISO/AAR format and Intellitag 500 (Gamma) RFIDs.